Safety shredder with mechanical bin-full device

ABSTRACT

A mechanical bin-full device for a paper shredder with a bin, having a curved, perforated T-blade sensor on a cylindrical body partially covered with a metal sheet. The T-blade is pendent into the bin. Metal contacts are placed on the paper shredder near the metal sheet, forming a switch, which is coupled to a motor control circuit for the shredder motor. The T-blade is pushed by paper shreddant and rotates the cylinder body as paper shreddant fills the bin. When the bin becomes full, the T-blade is positioned so that the metal contacts touch the metal sheet, closing the control circuit switch, and causing the motor to cease operating. The control circuit can include a microcontroller coupled to the motor, or a transistor-based driver coupled to a motor relay.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. application Ser. No.13/850,993, filed Mar. 26, 2013, which claims priority of Jan. 15, 2013to CN201310014059.1, CN201310014035.6, and CN201310014063.8 (all filedthe same day), each of which is hereby incorporated by reference in itsentirety.

BACKGROUND

1. Field of the Invention

The present invention relates to paper shredder, in particular, to amechanical bin-full device of paper shredder.

2. Background Art

The shredder presently is a machine that is commonly used to destroyconfidential documents. Generally, the shredder comprises apaper-shredding device and a waste bin. A fully-filled waste bin makesit difficult to continue the paper shredding, and high-piled scrapseasily damage the paper-full detection device. The existing paper-fulldetection devices chiefly comprise two types: a mechanical one and anelectronic one. The electronic paper-full detection device is fairlyexpensive and unstable, while the currently existing mechanicalpaper-full detection device has the shortcomings of being complicated instructure and inflexible to use.

In view of energy saving and safety, the shredder is usually providedwith a time-delay switch and a safety switch of power-off function whenthe shredder head is lifted, but normally these two switches areinstalled separately, thus increasing the number of parts for theshredder and the manufacturing cost.

Meanwhile, the existing paper-full devices are individually set, thus asimply structured and easily operated paper-full mechanism that is ableto be combinatorially set with other devices, such as the safety switchor time-delay switch for the shredder, with the power-off protectionfunction actuating upon machine/bin separation, is needed.

SUMMARY

The embodiments herein provide a simple, inexpensive, and durablesolution by implementing a mechanical bin-full detector.

A shredder is provided, having a shredder element, a bin, and a T-bladesensor. The shredder element has blades driven by an electric motor. Theshredder element also has shredder input to the blades and a shredderoutput from the blades. The shredder input receives shreddables. Theshredder output produces shreddant when the electric motor is operating.The bin is mechanically coupled to the shredder element, and receivesthe shreddant. The T-blade sensor is mechanically coupled to, and setapart from, the shredder element. The T-blade sensor also iselectrically coupled to the electric motor. The T-blade sensor rotatesto a predefined position to select an electrical contact such that theelectric motor is non-operating when shreddant reaches a predeterminedlevel in the bin. In embodiments, the T-blade sensor comprises a pendentblade perpendicularly affixed to a cylindrical body. The cylindricalbody has an electrical sensor thereon, which is configured toelectrically connect with electrical contacts on the shredder element.In other embodiments, the pendent blade is curved. In still otherembodiments, the curved pendent blade is perforated with a plurality ofholes.

In embodiments, the electrical sensor and electrical contacts form aswitch coupled to the electrical motor. In some embodiments, amicrocontroller is coupled to the switch. The microcontroller isconfigured to stop the electric motor when the T-blade sensor rotates tothe predefined position and the switch is closed. In other embodiments,The microcontroller is configured to stop the electric motor when theT-blade sensor rotates to the predefined position and the switch isopen.

In yet other embodiments, the switch is coupled between VCC and a firstvoltage divider resistor, the first voltage divider resistor is coupledto a first node, and the first node is coupled to a second voltagedivider resistor. The first node is coupled to a base of a firsttransistor, and the second voltage divider resistor is coupled toground. Also, a biasing resistor is coupled between VCC and a collectorof a first transistor through a second node, the second node beingcoupled to a base of a second transistor, and an emitter of the firsttransistor is coupled to ground. Further, a motor relay is coupledbetween VCC and a collector of the second transistor, and an emitter ofthe second transistor is coupled to ground. In one condition, with theswitch open, the motor relay is disposed to allow the electric motor tooperate. However, in another condition, with the switch closed, themotor relay is disposed to disable the electric motor from operating.

DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention disclosed herein are illustrated byway of example, and are not limited by the accompanying figures, inwhich like references indicate similar elements, and in which:

FIG. 1 is the cross-section view for the mechanical bin-full device ofpaper shredder in an embodiment, according to the teachings of thepresent invention;

FIG. 2A and FIG. 2B are cross-sectional diagrams for a paper shreddermechanical bin-full device in a first and a second embodiment, accordingto the teachings of the present invention;

FIG. 3 is a cross-sectional diagram of a third embodiment of amechanical shredder bin-full device, according to the teachings of thepresent invention;

FIG. 4 is a perspective drawing of an arc-shaped pressing plate asdescribed for the third embodiment, according to the teachings of thepresent invention;

FIG. 5 and FIG. 6 are cross-sectional drawings of the shreddermechanical bin-full device of the third embodiment, according to theteachings of the present invention;

FIG. 7 and FIG. 8 are cross-sectional drawings of another shreddermechanical bin-full device implementation as illustrated in a thirdembodiment, according to the teachings of the present invention;

FIG. 9 is a perspective view drawing of the fourth embodiment of ashredder mechanical bin-full device, according to the teachings of thepresent invention;

FIG. 10 is a perspective view drawing of the connecting rod and itsconnection relationship described in a fourth embodiment, according tothe teachings of the present invention;

FIG. 11 is a perspective view drawing of the connecting rod and safetyswitch linkage as described in a fourth embodiment, according to theteachings of the present invention;

FIG. 12 is a cross-sectional drawing of the paper-full detectionfunctions of the shredder mechanical bin-full device as described in afourth embodiment, according to the teachings of the present invention;

FIG. 13A and FIG. 13B are cross-sectional drawings of the paper-fulldetection functions of the shredder mechanical bin-full device of thefourth embodiment, in accordance with the teachings of the presentinvention;

FIG. 14 is a perspective view drawing for the time-delay switch and thesafety switch of the shredder in the prior art;

FIG. 15 is a perspective view of the time-delay mechanism of shredderintegrated with a safety switch in an embodiment, according to teachingsof the present invention;

FIG. 16 is a perspective view of the time-delay mechanism embodimentwhen the shredder head deviates from the paper waste bin, according toteachings of the present invention;

FIG. 17 is a perspective view drawing for parts of the time-delaymechanism of the embodiment of this invention after the shredder head isput into the paper waste bin, according to teachings of the presentinvention;

FIG. 18 is a perspective view drawing for parts of the time-delaymechanism of the embodiment of this invention during paper entry,according to teachings of the present invention;

FIG. 19 is a perspective view drawing for revolution of the time-delaymechanism in the paper shredding process in the embodiment, according toteachings of the present invention;

FIG. 20 is a perspective view drawing for parts of the time-delaymechanism of the embodiment of this invention when the paper fullyenters into the shredder and the contact part returns and delays,according to teachings of the present invention;

FIG. 21 is a perspective view drawing of the time-delay mechanism of theembodiment of this invention when the time-delay switch body disconnectsfollowing the end of time delay, according to teachings of the presentinvention;

FIG. 22 is a cut-away side view of a shredder, in accordance with anembodiment of the present invention;

FIG. 23A is a perspective view of a T-blade sensor in the shredderenabled position, in accordance with the teachings of the presentinvention;

FIG. 23B is a perspective view of the T-blade sensor of FIG. 2A in theshredder disabled position, in accordance with the teachings of thepresent invention;

FIG. 24 is a cut-away front view of a shredder having a T-blade pendenttherefrom, in accordance with the teachings of the present invention;

FIG. 25 is a cut-away perspective view of the shredder of FIG. 24, witha bin coupled to the shredder, in accordance with the teachings of thepresent invention;

FIG. 26 is a microcontroller implementation of control circuit for ashredder electric motor, in accordance with the teachings of the presentinvention; and

FIG. 27 is a two-transistor implementation of a control circuit for ashredder electric motor, in accordance with the teachings of the presentinvention.

Skilled artisans can appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to helpimprove the understanding of the embodiments of the present invention.In the figures, like numbers correspond to like elements.

DETAILED DESCRIPTIONS OF THE EMBODIMENTS

Below is an explanation of technical protocols for this inventionthrough selected embodiments, but the following embodiments cannot limitthe scope of protection of this invention.

Example Embodiment 1

In FIG. 1, the mechanical bin-full device of a paper shredder in thisembodiment includes a pressing plate 1, a contact switch 2, and atouching part, which can be touching plate 11. Pressing plate 1 can beinstalled at the outside of the mechanical parts of the shredder underthe lower housing 3 of the shredder, and parallel to the cutter shaft ofthe mechanical parts of the shredder, one end of which is connected tothe lower housing 3 of the shredder through pivoting connection, such asrotation shaft, and the other end can freely swing. In other embodimentsof the present invention, the pressing plate may be not parallel to thecutter shaft of the shredder. It can present a smaller, more acute,angle with the cutter shaft of the shredder.

A contact switch 2, fixed on the lower housing 3 of the shredder, and acontact point 21 is provided on one side of the contact switch 2 whichis near the lower housing 3 of the shredder; the contact switch 2 is amicro-switch in this embodiment. A touching part is provided on one sideof the pressing plate 1 which is away from the mechanical parts of theshredder, and in this embodiment, the touching part is installedperpendicular to the surface of the pressing plate 1; preferentially, inthis embodiment, the touching part is a touching plate 11, which isprovided with a tip part 111 which is used to touch the contact point 21of the contact switch 2. The lower housing 3 of the shredder is providedwith a through-hole 31 under the contact point 21 of the contact switch2, enabling the touching plate 11 to touch the contact point 21 ofcontact switch 2, and under the driving of paper waste cumulated in thepaper waste bin of the shredder, the pressing plate 1 turns around therotation shaft, making the touching plate 11 installed on the pressingplate 1 touch the contact point 21 of contact switch 2 and making theshredder power off and stop running. In this embodiment, the crosssection of the pressing plate 1 can be arc-shaped, which backs to themechanical parts of the shredder, and the touching plate 11 can beinstalled in the inside of the arc-shaped pressing plate 1. In addition,in this embodiment, the pressing plate 1 has multiple holes, which canbe arranged evenly. In this embodiment, these holes are long holes andin other embodiments they also can be round holes or any other suitableholes of any shape. In this embodiment, the width of pressing plate 1can be shorter than the length of the cutter shaft of shredder, forexample, its width can be from about ⅕ to about ⅓ of the length of thecutter shaft of shredder, and typically the pressing plate 1 can beinstalled in a position close to the middle. That the width of pressingplate is shorter than the length of the cutter shaft of shredder notonly saves the material and makes it more portable. This configurationmakes the pressing plate easily uplifted by the shredded paper as paperaccumulates. It also reduces the probability of the pressing plate beingdamaged in the transportation process. When the pressing plate is set atthe middle, the sensitivity of the paper shredder mechanical bin-fulldevice is increased.

Referring to FIG. 2A, when the paper shredder begins to run, theshredded paper waste 4 are minimal and the pressing plate 1 generally isnot pressed, thus allowing the shredder to continually work. Duringshredding, shredded paper waste 4 is increased. When waste 4 reaches acertain volume, shredded paper waste 4 can drive the pressing plate 1,making the pressing plate 1 turn along the connecting shaft of thepressing plate 1 and the lower housing 3 of shredder. As the height ofshredded paper waste 4 increases, it continues to push forward thepressing plate 1, making the tip part 111 of the touching plate 11 onthe pressing plate 1 rise until the tip part 111 touches the contactpoint 22 of contact switch 2, shown in FIG. 2B, which makes the shredderpower turn off and the shredder stop running. At that time, the user canclear away the shredded paper in the paper waste bin, and thereafter,because there is no pushing force of shredded paper waste, the pressingplate 1 will return and fall to its natural status, ready for the nextcycle of paper shredding.

Example Embodiment 2

The difference of this embodiment from example Embodiment 1 is that thetouching part installed on the pressing plate is a touching rod.

Example Embodiment 3

As shown in FIG. 3-6, the shredder in this embodiment includes themechanical parts of the shredder 101, the lower housing 102 of theshredder, as well as the shredder mechanical bin-full device. FIG. 5 andFIG. 6 are cross-sectional drawings of the application processes of thepaper-full detection functions by the shredder mechanical bin-fulldevice. FIG. 7 and FIG. 8 are drawings of the structure by anothermechanical bin-full device of shredder and on the application processesof the paper-full detection functions by another implementation of ashredder mechanical bin-full device.

The mechanical bin-full device of this embodiment chiefly consists of acontact switch, a touching device, and a pushing device. The contactswitch, which is a safety switch 103 in this embodiment, may be fixedlyinstalled on the lower housing of the shredder 102. The safety switch103 is equipped with a contact point 131 that is to be contacted whenthe shredder head is put into the waste bin so that the shredder ispowered on to function. When the shredder head separates from the wastebin, the contact point 131 of the safety switch 103 is released, thusenabling the shredder to be powered off. Whether the contact point 131is trigged or not is used by the safety switch 103 to control thepower-on or power-off for the shredder.

A touching device, which is a poke rod 104 in this embodiment, cancontact or depart from the contact point 131 of the safety switch 103,thus enabling the shredder to be powered on or powered off, detailing inthis embodiment as follows: the lower housing of the shredder 102 is setwith a through hole 121 in the corresponding position under the contactpoint 131 of the safety switch 103. One end of the poke rod 4 passesthrough the through hole 121, ensuring the contact point 131 of thesafety switch 103 to be contacted or released (e.g. released by the pokerod being pushed to move). The other end of the poke rod 104 isinstalled by a support 105 at the inner side of the shredder waste bin,wherein the support 105 can either be detachably mounted to the innerside of the shredder waste bin, or may be nondetachably fixed to theinner side of the shredder waste bin, or be integrally molded byinjection along with the shredder waste bin. The poke rod 104 ispivotally connected to the support 105 through a rotation axis and itcan rotate around the support 105 within a definitive scope.

The rotating scope of the poke rod 104 is limited by a first restrictionmember and a second restriction member placed on the support 105. Inthis embodiment, both the first restriction member and the secondrestriction member are limit bars, marked as the limit bar 151 and thelimit bar 152. The limit bar 151 is transversely installed on thesupport 105. The poke rod 104 has a vertical part 141, one side surfaceof which is prop up one end of the limit bar 151. The relative positionof the limit bar 151 and the vertical part 141 is set to ensure that thepoke rod 104 can touch the contact point 131 of the contact switch 103when the shredder is in the normal working condition, and preventing thepoke rod 104 from suffering the deviation from the position of thecontact point 131 that is incurred due to its downward rotation byaction of gravity. The limit bar 152 is used for restricting the movingdistance of the poke rod 104 from the contact point 131 of the safetyswitch 103 upon the poke rod 104 being pushed, and set parallel to thelimit bar 151. Certainly, the limit bar 151 and the limit bar 152 arenot necessarily set parallel to each other, their setup manners canutilize any other ones that are suitable to play the same roles.Moreover, the limit bar 152 is not necessarily set components butoptional. This is illustrated only for explanation, but not fordefinition.

The pushing device, which can be an arc-shaped pressing plate 106 inthis embodiment, one end of which is pivotally installed through arotation axis under the lower housing of the shredder 102 at the outerside of the mechanical parts of the shredder 101, and the other end ofwhich is a free end. The cambered surface of arc-shaped pressing plate106 backs to the mechanical parts of the shredder 101, and the pressingplate 106 is equipped with a touching element, which is a touching sheet161 in this embodiment. The touching sheet 161 is installed in thedirection perpendicular to the plate surface of the arc-shaped pressingplate 106, wherein one end of the touching sheet 161 is connected to theplate surface of the arc-shaped pressing plate 106, and the other endhas a tip part 611 that can push the poke rod 104 when the paper wasteinside the shredder waste bin pushes the arc-shaped pressing plate 106to rotate, enabling the poke rod 104 to depart from the contact point131 of the safety switch 103.

Typically, the width of the arc-shaped pressing plate 106 is less thanthe length of the cutter shaft of the shredder. For example, the widthof the arc-shaped pressing plate 106 can be between about ⅕ to about ⅓of the length of the cutter shaft of the shredder. Furthermore, thearc-shaped pressing plate 106 can be set under the lower housing of theshredder 102 and, at the side, aligned with the cutter shaft of theshredder and close to the middle. That the width of the pressing plateis less than the length of the cutter shaft of the shredder enables theweight of the arc-shaped pressing plate to be reduced, easy to be pushedby the shredded paper waste piled inside the waste bin, leading to moresensitive detection. This also can decrease the probability of thepressing plate being damaged in the course of transportation. That thepressing plate is placed in the middle part enables the shredded paperwaste filling in the waste bin to be more effectively and accuratelydetected.

In this embodiment, the arc-shaped pressing plate 106 is configured withmultiple holes. These holes may be waist-shaped. Also, as shown in FIG.6, these holes may be evenly arranged. The setup of multiple holes cansignificantly reduce the weight of the arc-shaped pressing plate 106.The weight-reduction enables plate 106 to more easily to be pushed bythe paper scrap gradually accumulating inside the waste bin, thusimproving the sensitivity in terms of the paper-full detection. Theconfiguration of evenly arranged holes with the same shapes can bettercontribute to processing and manufacturing.

In this embodiment, the principles that the shredder mechanical bin-fulldevice is applied to achieve the power-off protection functionsaccording to shredder head lifting are explained as below: As shown inFIG. 5, when the shredder head is put into the waste bin, one end of thepoke rod 104 just contacts the contact point 131 of the safety switch103 which powers on the shredder to initiate operation. When theshredder head is lifted, one end of the poke rod 104 departs from thecontact point 131 of the safety switch 103, powering off the shredder toterminate operation.

In this embodiment, the principle and process that the mechanicalbin-full device applied to the shredder with the integral waste bin toachieve the paper-full detection function are described as below: Asshown in FIG. 7 and FIG. 8, when the paper shredding starts, thequantity of the paper waste 107 is fairly small. Therefore, thearc-shaped pressing plate 106 is not pressed and the shredder remains inthe power-on state to continue working (see FIG. 7). With the gradualincrease of the paper waste 107 inside the waste bin, when the quantityof the paper waste 107 becomes enough to push the arc-shaped pressingplate 106, the arc-shaped pressing plate 106 will rotate around the axisof it and the lower housing of the shredder 102. When it rotates to apreselected angle, the tip part 611 of the touching sheet 161 on thearc-shaped pressing plate 106 will contact and push the poke rod 104,enabling it to rotate around the support 105, thus enabling the poke rod104 to release the contact point 131 of the safety switch 103 (see FIG.6). In such case, the shredder is powered off to cease operation, whichreminds the user that the paper waste bin are full and that it isnecessary to pour out the waste for the continuing work of the shredder.After the paper scraps are poured out, the poke rod 4 will go back tothe original position because of gravity. Because of the limiting actionof the limit bar 151, the poke rod 104 can just contact the contactpoint 131 of the safety switch 103 when the shredder head is put intothe waste bin so that the shredder can be powered on to operation.

The mechanical bin-full device also can be used on the shredder with thedrawing-type waste bin, realizing the functions of power-off protectionof machine/waste bin separation and paper-full detection. The structureof poke rod 104 can be modified slightly with respect to such functions,as is described with respect to FIG. 7. There is a branch componentdisposed on the poke rod 104 through pivot connection, e.g. a branch rod142, one end of which is connected to the poke rod 104 via pivoting andthe other end is connected to the lower housing of the shredder throughpivot connection. Under such structure, principle for power-offprotection function of machine/waste bin separation is as follows: inFIG. 7, when the waste bin is drawn out, the poke rod 104, under thefunction of its own gravity, departs from the contact point 131 of thesafety switch 103, and the shredder powers off. In FIG. 8, when thewaste bin is pushed into the waste bin accommodation space below theshredder, the limit bar 151 which is set on support 105 of the waste binpushes the vertical part 141 of the poke rod 104, enabling the poke rod104 to turn along the shaft of the poke rod 104 and the branch rod 142as well as along the shaft of the branch rod 142 and the lower housingof the shredder. This action enables the upper end of the poke rod 104to touch the contact point 131 of the safety switch 103, thereforepowering on the shredder. In this embodiment, the principle forrealization of paper-full detection function by the mechanical bin-fulldevice of shredder including the above-mentioned improvement structureof poke rod applied to the integral waste bin of the shredder is asfollows: when paper waste is not full in the waste bin of the shredder,the mechanical bin-full device maintains the same state as that when thewaste bin is pushed into the accommodation space under the shredder.When the paper waste increases and pushes the arc-shaped pressuringplate 106 to turn to push poke rod 104, and poke rod 104 turns along thepivot of it and the branch rod 142, therefore, enabling the upper end ofthe poke rod 104 to depart from contact point 131 of the safety switch103 and the shredder power off. At this point, paper waste in the wastebin can be poured out, so that paper shredding and paper-full detectioncan be carried out again.

By carrying out of paper-full detection test on the above mentionedmechanical bin-full device of shredder, it has been demonstrated thatthe device possesses favorable paper-full detection function, togetherwith the function of excellent power-off protection during machine/wastebin separation.

Example Embodiment 4

As shown in FIG. 7-10, the shredder in this embodiment includes themechanical parts of the shredder (not shown in the Figures), the lowerhousing 102 of the shredder, as well as the mechanical bin-full deviceof shredder. As shown in FIG. 7, the mechanical bin-full device for theshredder of this embodiment mainly includes a contact switch, a touchingdevice, and a pushing device. The contact switch, which is a safetyswitch 103 in this embodiment, may be fixedly installed on the lowerhousing 102 of the shredder. The safety switch 103 can be equipped witha contact point 131 that is contacted when the shredder starts normally,and operates. Upon the shredder head separating from the waste bin, thecontact point 131 of the safety switch 103 is released, thus enablingthe shredder to be powered off. Whether the contact point 131 is triggedor not is used by the safety switch 103 to control the power-on orpower-off of the shredder;

The touching device, which is a connecting rod 108 in this embodiment,is connected to the lower housing 102 of the shredder, the connectingrod 108 is set with a first end 181 and a second end 182, and the secondend 182 is set with a elastic component, which is a spring 183 in thisembodiment. There is a bar set at the waste bin corresponding to thesecond end 182 of the connecting rod 108. Through spring 183, connectingrod 108 can contact the contact point 131 of the safety switch 103 assqueezed by the bar of corresponding position set on the waste bin ofthe shredder (see FIG. 8), in detail, the lower housing 102 of theshredder is set with fixed connecting rod holder 122 which limits themovement of connecting rod 108, the connecting rod holder 122 includestwo identical parts which are set separately at both sides of theconnecting rod 108, and each part is set with a long shaped slot, forexample, kidney-shaped slot 221. The connecting rod 108 is set with twocolumnar convex elements 184 and 185 which are adaptable to thekidney-shaped slots 221 (see FIG. 9). The two columnar convex 184 and185 are assembled inside of the two kidney-shaped slots 221 respectivelyand can slide along the kidney-shaped slots 221.

Moreover, this structure also may serve as revolving shaft, enabling theconnecting rod 108 to turn along a direction perpendicular to theundersurface of the shredder lower housing within a small angle range.The connecting rod 108 is also set with restriction convex, and thespring 183 is sheathed on the connecting rod 108, for detail, one end ofthe spring 183 is resisted against the connecting rod holder 122 of theshredder lower housing, with the other end resisted against therestriction convex disposed on the connecting rod 108. Because the wastebin of the shredder is set with a bar 109 at the second end of thecorresponding connecting rod 108, and the lower housing of the shredderis set with through holes at the corresponding positions of the bottomsurface. When the shredder is put into the waste bin, the bar 109 cansqueeze the second end 182 of the connecting rod 108 inward, thereby,pushing the first end 181 of the connecting rod 108 to contact thecontact point 131 of the safety switch 103, enabling the shredder topower on, at the moment spring 183 is compressed. When lifting the lowerhousing 102 of the shredder, one end of the spring 183 is resistedagainst the connecting rod holder 122 on the lower housing of theshredder, while the other end pushes away the restriction convex on theconnecting rod 108 via the resilience force, thereby, pushes away theconnecting rod 108, enabling the first end 81 of the connecting rod 108to depart from the contact point 131 of the safety switch 103, and then,the shredder is powered off. The abovementioned is the principle ofmechanical bin-full device applied for the power-off protection functionof machine/waste bin separation to the integral waste bin shredder ofthis embodiment. If it is applied to the shredder with the drawing-typewaste bin, the bar may be set on the drawing-type waste bin, and throughholes may be set at the positions corresponding to the lower housingsides of shredder. When pulling the drawing-type waste bin away, the baron the drawing type waste bin releases the connecting rod 108, enablingthe shredder to be powered off; when pushing in the drawing-type wastebin, the bar on the drawing type waste bin presses the connecting rod108, thus pushing the first end 181 of the connecting rod 108 to contactthe contact point 131 of the safety switch 103, enabling the shredder topower off. Besides, the lower part of the connecting rod 108 is set witha convex part 186. When pushing the convex part 186 upon paper fullcondition, the connecting rod 108 can turn a certain angle along thedirection which is vertical to the lower housing of the shredder,enabling the first end 181 of connecting rod 108 to depart from thecontact point 131 of the safety switch 103, achieving the effect ofenabling the shredder to power off.

The pushing device, which can be an arc-shaped pressing plate 106, oneend of which is pivotally installed through a rotation axis at the outerside of the mechanical parts of the shredder (not shown) under the lowerhousing 102 of the shredder, and the other end of which is the free end.The cambered surface of the arc-shaped pressing plate 106 backs on tothe mechanical parts of the shredder (not shown), in which is equippedwith a touching element, which is a touching sheet 161 in thisembodiment. The touching sheet 161 is installed in the directionsubstantially perpendicular to the plate surface of the arc-shapedpressing plate 106, one end of which is connected to the plate surfaceof the arc-shaped pressing plate 106, and the other end of which has atip part 611 that can push the convex part 186 of the connecting rod 108when the shredded paper waste inside the shredder waste bin pushes thearc-shaped pressing plate 106 to rotate, enabling the convex part todepart from the contact point 131 of the safety switch 103.

In this embodiment, width of the arc-shaped pressing plate 106 is lessthan the length of the cutter shaft of the shredder. The typical widthof the arc-shaped pressing plate 106 is between about ⅕ to about ⅓ ofthe length of the cutter shaft of the shredder. The arc-shaped pressingplate 106 is set under the lower housing 102 of the shredder where it ispositioned at the side aligned with the cutter shaft of the shredder andclose to the middle. In this embodiment, the arc-shaped pressing plate106 typically is set slightly near the connecting rod 108. Thearc-shaped pressing plate 106 is configured with several holes which canbe waist type holes arranged evenly (see FIG. 2). The set of severalholes may notably reduce the weight of the arc-shaped pressing plate106, enabling it to be more easily pushed by the shredded paper wastewhich is gradually accumulated in the waste bin, improving itssensitivity to detect the filling state of waste paper.

The shredder mechanical bin-full device is set on the lower housing 102of the shredder, therefore, operating principles for it to be used onthe shredder with the integral waste bin and shredder with thedrawing-type waste bin are similar. The specific principle and processare that: (see FIG. 12, FIG. 13A and FIG. 13B), when the paper shreddingjust starts, the volume of paper waste 107 is small, therefore,arc-shaped pressing plate 106 is not pressed, the shredder maintains thepower-on status and operates continuously. With the gradually increasingof paper waste 107 in the shredder, when the paper waste reaches certainvolume, it touches the arc-shaped pressing plate 106. The arc-shapedpressing plate 106 rotates around the shaft of the plate 106 and thelower housing 102 of the shredder, enabling the top part 611 of thetouching sheet 61 to contact the convex part 86 of the connecting rod108 (see FIG. 10). With the gradual increasing of the paper waste 107,it gradually pushes the arc-shaped pressing plate 106 to revolve, andthe top part 611 of the touching sheet 161 of the arc-shaped pressingplate 106 lifts up the convex part 186 of the connecting rod 108 (seeFIG. 13A), enabling it to revolve upward and depart from the contactpoint 131 of the safety switch 103 (see FIG. 13B), upon which theshredder is powered off and shuts down. The user is alerted that thepaper waste is full and the shredder can only go on working when thepaper scrap is poured out. When the paper waste is poured out, and thewaste bin is pushed in or placed to its original place, the first end181 of the connecting rod 108 contacts the contact point 131 of thesafety switch 103 to proceed to the next paper shredding circulation.

FIG. 13A and FIG. 13B are drawings based on the application processes ofthe paper-full detection functions by the mechanical bin-full device ofshredder as described in the fourth embodiment, which respectively showsthe conditions of the safety switch and connecting rod from differentperspectives when the shredder is powered off.

All the components of the mechanical bin-full device for the shredder ofthis embodiment are set on the lower housing of the shredder, with awider range of shredder model applicable and not limited by the set modeof the waste bin of the shredder.

Example Embodiment 5

Turning to FIG. 14, a prior art shredder head is shown includingseparate time-delay switch 301 and safety switch 303 is shown. Requiringseparate elements for the time delay switch and safety switch canincrease costs and decrease reliability. The embodiments of the presentinvention provide for an integrated time-delay and safety switch.

Referring to FIGS. 15 and 16, in this embodiment, the time-delaymechanism of shredder integrated with a safety switch of power-offfunction according to the lift of the shredder head, includes atime-delay switch body 201, which is pivot-connected to the side plate212 of the shredder through a connecting pivot 210. The time-delayswitch body 201 is provided with a forced rod 202. The paper waste binof the shredder is provided with a support rib 231 (not shown in FIG.15, see FIGS. 17-21) at the location corresponding to the forced rod202. One end of the forced rod 202 is connected to the time-delay switchbody 201 through pivoting connection and the other end is connected tothe support rib 231 (not shown in FIG. 15, see FIGS. 17-21) by means oftouch. When the shredder head is put into the paper waste bin, under thedriving of the support rib 231, the forced rod 202 can drive thetime-delay switch body 201 to rotate and leave it in contact state withthe paper entrance. In this embodiment, the time-delay switch body 201includes a contact piece 211, which rotates and joints to the time-delayswitch body 201 and makes the time-delay switch body 201 closed, and thecontact piece 211 revolves and deviates from the time-delay switch body201 and makes it open. The forced rod 202 is provided with a ring-likeassembly 21 (not shown in FIG. 15, see FIGS. 16-17) at one end where itis connected to the support rib 231 by means of touch. The ring-likeassembly 221 (not shown in FIG. 15, see FIGS. 16-17) is installed on ahollow cylinder 241 (not shown in FIG. 15, see FIG. 16) set at the lowerhousing of the shredder and its tail end stretches into the cavity ofthe hollow cylinder 241 (not shown in FIG. 15, see FIG. 16). The aboveinstallation mode of the tail end of the forced rod which is connectedto the support rib by means of touch and the lower housing of theshredder is only an example. Any suitable structure in which the supportrib on the paper waste bin of the shredder can lift up the forced rodand then make the time-delay switch body 201 rotates and keep in thecontact state in case of paper entering is within the scope of thisinvention.

In this embodiment, the time-delay mechanism of shredder integrated witha safety switch typically includes a contact component with the paperentrance, which includes a contact part 251 at paper inlet, a connectingrod 252 and a push button 253. Two ends of the connecting rod 252 arefixed respectively to the contact part 251 at paper inlet and the pushbutton 253, and the push button 253 can drive the time-delay switch body201 during entering of paper and make it closed.

The time-delay mechanism also typically includes a time-delay component,which includes a cam 206 and a gear 207. The cam 206 and the gear 207generally rotate synchronously in the same direction, and the gear 207is engaged with the cutter shaft gear 209 of the shredder through areduction gear 208.

The working principle and process for the time-delay mechanism ofshredder integrated with a safety switch of this embodiment are asfollows: referring to FIG. 16, when the shredder head deviates from thepaper waste bin, the forced rod 202 is not driven by the support rib 231(not shown in FIG. 16, see FIGS. 17-21). The time-delay switch body 201revolves downwards along the connecting shaft 10 due to its gravity andmakes the contact piece 211 on it depart from the time-delay switch body201, making the time-delay switch body 201 open, and then the shredderis powered off. When the shredder head is put into the paper waste bin,the tail end 221 of the forced rod 202 is lifted up by the support rib231 on the paper waste bin and makes the forced rod 202 uplift. Underthe upward pushing force, the time-delay switch body 201 revolves to apreselected angle around the connecting shaft 10, which makes thetime-delay switch body 201 achieve the deflection angle at which theshredder does not shred any paper in the normal state, i.e. the contactstate when is paper entering, as shown in FIG. 7. When there is paperput at the paper inlet, the contact part 251 at paper inlet is depressedby the paper and makes the push button 253 revolve upwards through theconnecting rod 252. This action drives the contact piece 211 of thetime-delay switch body 201 and makes it rotate and joint to thetime-delay switch body 201, thus making the time-delay switch body 201closed. Then, the shredder is powered on and begins the paper shredding,as shown in FIG. 18. In the paper shredding process, the time-delaycomponent (the cam 206 and the gear 207 revolving in the same direction)turns with the rotation of the cutter shaft of the shredder under thedriving action of the shredder cutter shaft gear 209 and the reductiongear 208, as shown in FIG. 19. When the paper fully enters into themechanical part of the shredder, the contact part 251 at paper inletbounces and begins the time delay. The cam 206 of the time-delaymechanism of the shredder resists the contact piece 211 of thetime-delay switch body 201, and so the shredder remains powered on andits cutter shaft continues to revolve, thus the cam 206 revolves aswell, as shown in FIG. 20. The contact piece 211 leaves the time-delayswitch body 201 due to its gravity and makes the time-delay switch body201 open, until the cam 206 revolves to departing from the contact piece211 of the time-delay switch body 201 and cannot resist the contactpiece 211, ending the time delay, as shown in FIG. 21. The shredder nowis powered off.

Through the installation of a forced rod, these embodiments uses oneswitch to achieve not only the power-off function according to the liftof the shredder head but also the contact function when paper entering,and also ensure the time-delay effect in paper shredding. It is easy foruse with high efficiency and saves cost as well.

Except for the above mode of execution, the idea that the time-delayswitch of shredder integrated with a safety switch installed on theforced rod which is linked with the shredder's paper waste bin is alsoapplied to any suitable time-delay mechanism with contact function whenpaper entering; the above embodiments are only used for illustrating thecontents of this invention; except for the above mode of execution, thisinvention has other modes of execution; all technical protocols formedin the mode of equal replacement or equivalent transformation are withinthe scope of protection of this invention.

Example Embodiment 6

Turning to FIG. 22, shredder 300 has input opening 310, shreddingelement with moving blades 320, and output opening 330. The shreddingelement blades 30 are motivated by an electrical motor 340 mechanicallycoupled thereto. Shredding occurs when motor 340 is electricallyenergized. Shredder 300 receives shreddable products (shreddables) andproduces shredded material (shreddant) 350 Shredding element 320 can bedisposed upon a bin 360 intended to receive shreddant created by theshredding element.

Turning to FIG. 23A, and also with reference to FIG. 22, T-blade 400 canhave pendent blade portion 410 and cylindrical body 420. T-blade 400 canbe disposed set apart from the shredder output opening 330. Pendentblade portion 410 may partially intrude into the bin 360, but it is notrequired to do so. Pendent blade portion 410 can be formed with curve450. Cylindrical body 420 can include conductive endpiece 430 andnon-conductive portion 440. In embodiments, conductive endpiece 430 maybe a non-closed annular metal sheet 480 partially disposed oncylindrical body 420, which may be non-conductive. Sheet 480 may becopper, but it is not required to be. T-blade 400 can act as a bin-fullsensor.

Dielectric flat 495 can have a plurality of metal contacts 470, 471extending therefrom. Gap 465 can be interposed between metal contacts470, 471 so that they are not in electrical contact. One metal contact470 can be electrically coupled to electric motor 340. The other metalcontact 471 can be electrically coupled to electrical ground (ground).Together, metal contacts 470, 471 and conductive endpiece 430 can forman electrical switch by which to operate shredder motor 340. Contacts470, 471 further may be bent and pressed to improve contact, when made,with conductive endpiece 430. Plural pairs of metal contacts may be usedand, if so, they can be symmetrically spaced apart.

During shredding, blade portion moves linearly, which is translated torotational movement by cylindrical body 420. When endpiece 430 rotates,the annular metal sheet 480 can be urged toward metal sensors 470, 471,and ultimately can touch metal contacts 470, 471, when bin 360 is full.Curve 450 can be shaped to permit shreddant 350 to easily move asideT-blade 400, without being immobilized, by the growing mass of shreddant350. When pressed upon by shreddant 350 accumulating in bin 360, curvedT-blade 400 pivots in a plane generally perpendicular to thelongitudinal axis of the cylindrical body 420.

Pressure from shreddant 350 tends to urge T-blade 400 generally to theright along line 460. By filling bin 360 with shreddant 350, T-blade 400can be moved from the “ON” (or “RESET”) position, when empty, to the“OFF” (or “FULL”) position, when full. As illustrated in FIG. 23B,conductive endpiece 430 can be separated from contacts 470, 471. In thiscase, a corresponding switch (not shown) is open, and a circuit (notshown) coupled to electrical motor 340 can be energized. Duringshredding, as curved T-blade 400 is forced towards the “OFF” position,conductive endpiece 430 is urged towards contacts 470, 471. When the binis full at a predetermined level, contacts 470, 471 touch conductiveendpiece 430, and the corresponding switch is closed. The completedcircuit causes power to be removed from electrical motor 430 by thecircuit, ceasing shredding. Dielectric flat 495 may be physicallycoupled to a PCB (not shown), bearing the control circuit (not shown)for motor 340.

In embodiments, curved T-blade 400 can have ring-type torsional spring475 on non-conductive portion 440 of cylindrical body 420, which ispositioned to bias T-blade 400 to the “ON” (or “RESET”) position whenthe bin 360 is empty. In this state, conductive endpiece 430 is nottouching contacts 470, 471. By filling bin 360 with shreddant 350, thespring 475 bias on T-blade 400 can be overcome by the force of theaccumulating shreddant 350 until T-blade 400 is moved to the“OFF”/“FULL” position when shredder bin 360 can be considered to befull. In the “OFF”/“FULL” position, conductive endpiece 430 can touchcontacts 470, 471. Spring 475 may be a tension spring or compressionspring, although other mechanical biasing devices may be used.

In other embodiments, instead of a spring-loaded reset, a gravity resetalso can be used. For example, from the “ON”/“RESET” position,accumulating shreddant 350 gradually fills bin 360, pressing uponT-blade 400 and forcing it against gravity to the “OFF”/“FULL” position,whereupon shredding is caused to cease. When bin 360 is emptied, gravitycan bring T-blade 400 to the “ON”/“RESET” position, removing contactbetween conductive endpiece 430 and contacts 470, 471 and allowing theshredder operation.

In an alternative embodiment, conductive endpiece 430 may be disposed tomake electrical contact with metal contacts 470, 471 while the bin isempty, and break electrical contact with metal sensor 470, 471, when thebin becomes full. In this configuration, a full bin 360 can cause anopen circuit by, which power can be removed from electrical motor 340.In other words, the functionality of the contacts can be reversed inalternative embodiments.

In embodiments, the pendent blade portion of T-blade 400 can beperforated, and may have a sufficient number, size, and distribution ofholes, generally at 490, to make the T-blade both strong andlightweight. Turning to FIG. 24, T-blade 400 may be held in place inshredder 300 by means of a first holder 560 and a second holder 570.Turning to FIG. 25, shredder 300 is shown separated from cut-away bin360, thereby exposing the location of T-blade 400. T-blade 400 can beheld in place by holders 560, 570, as shown in FIG. 24.

FIG. 26 illustrates one embodiment of control circuit 600 for electricalmotor 340, using PIC16F690 8-bit microcontroller 510 produced byMicrochip, Inc., Chandler, Ariz. USA. RA0, on pin 19, is a generalpurpose I/O port, which produces an interrupt to the microcontroller 510upon a change of the pin voltage state. VCC power 520 can beelectrically coupled to microcontroller 510 VDD pin, and microcontroller510 VSS pin 20 can be electrically coupled to ground 530. Switch S1 540is electrically coupled between RA0 pin 19 and ground 530. Switch S1 540may be composed of metal contacts 470, 471 and conductive endpiece 430.

When shredder 300 is in the “ON” state, switch S1 540 is “OPEN” and pin19 is provided an electrically pulled-up VCC-level signal throughbiasing resistor 550. Switch S1 540 also is a switch generallyrepresentative of the contact state of conductive endpiece 430 with atleast one metal contact 470. In embodiments, with bin 360 in thenot-full state, S1 remains “OPEN” and shredder functions are allowed toproceed. As bin 360 fills with shreddant, S1 remains “OPEN.” Uponcontact of conductive endpiece 430 with at least one metal contact 470,switch S1 540 is “CLOSED,” pulling down RA0/pin 19 to ground 530 andchanging its electrical state, thereby forcing an interrupt uponmicrocontroller 510. An interrupt routine for RA0/pin 19 pin canmanipulate the states of other pins on microcontroller 510, turning OFFelectrical motor 340, and ending shredding.

Embodiment 7

FIG. 27 depicts another embodiment of control circuit 600, which caninclude switch S2 610, voltage divider resistors R2 620, R3 630, biasingresistor R4 640, transistor Q1 650, transistor Q2 660, and motor relay670. Providing power is VCC 680. Ground is 690. Switch S2 610 may becomposed of metal contacts 470, 471 and conductive endpiece 430. In FIG.6, VCC 680 is electrically connected with switch S2 610, biasingresistor R4 640, and motor relay M 670. Switch S2 610 is connected tofirst voltage divider resistor R2 620, which is connected through node 1625 to second voltage divider resistor R3 630. Node 1 625 can beconnected to the Base of transistor Q1 650. Biasing resistor R4 640 isconnected to node 2 645 and to the Collector of transistor Q1 650. Node2 645 is connected to the Base of transistor Q2 660. Motor relay 670 isconnected to the Collector of transistor Q2 660. Second divider resistorR3 630 and the Emitters of transistors Q1 650 and Q2 660 are connectedto ground 690.

As above, when bin 360 is not full, S2 remains “OPEN,” causing the Baseof transistor Q1 650 to be connected to ground 690 through seconddivider resistor R3 630, turning “OFF” transistor Q1 650. VCC 680 biasesresistor R4 640 such that the Base of second transistor Q2 660 isenergized, turning “ON” transistor Q2 660. This causes current to flowthrough motor relay M 670, causing shredder motor 340 to be “ON” (orenergized). When bin 360 fills to a predetermined level, conductiveendpiece 430 contacts at least one metal contact 470, causing switch S2610 to be closed. With switch S2 610 closed, the voltage of the BASE oftransistor Q1 650 is raised through R2, causing transistor Q1 650 toturn “ON.” Turning “ON” transistor Q1 650 causes node 2 645, and theBase of transistor Q2 660, to be pulled to ground 690, thereby turning“OFF” transistor Q2 660. Turning “OFF” transistor Q2 660, shuts offmotor relay M 670 which, in turn, shuts “OFF” shredder motor 340

The example embodiments of the present invention disclosed herein areintended to be illustrative only, and are not intended to limit thescope of the invention. It should be understood by those skilled in theart that various modifications and adaptations of the prevent inventionas well as alternative embodiments of the prevent invention may becontemplated or foreseeable. It is to be understood that the presentinvention is not limited to the sole embodiments described above, butencompasses any and all embodiments within the scope of the followingclaims.

1. A shredder, comprising: a shredder element having blades driven by anelectric motor, a shredder input to the blades and a shredder outputfrom the blades, wherein the shredder input receives shreddables and theshredder output produces shreddant when the electric motor is operating;a bin mechanically coupled to the shredder element, wherein the binreceives the shreddant; a T-blade sensor mechanically coupled to and setapart from the shredder element, and electrically coupled to theelectric motor, wherein the T-blade sensor rotates to a predefinedposition to select an electrical contact such that the electric motor isnon-operating when shreddant reaches a predetermined level in the bin.2. The shredder of claim 1, wherein the T-blade sensor comprises apendent blade perpendicularly affixed to a cylindrical body, thecylindrical body having an electrical sensor thereon configured toelectrically connect with electrical contacts on the shredder element.3. The shredder of claim 2, wherein the pendent blade is curved.
 4. Theshredder of claim 3, wherein the curved pendent blade is perforated witha plurality of holes.
 5. The shredder of claim 2, wherein the electricalsensor and electrical contacts form a switch, coupled to the electricalmotor.
 6. The shredder of claim 5, further comprising: a microcontrollercoupled to the switch, wherein the microcontroller is configured to stopthe electric motor when the T-blade sensor rotates to the predefinedposition and the switch is closed.
 7. The shredder of claim 5, furthercomprising: a microcontroller coupled to the switch, wherein themicrocontroller is configured to allow the electric motor to turn onwhen the T-blade sensor rotates away from the predefined position andthe switch is open.
 8. The shredder of claim 5, further comprising: theswitch coupled between VCC and a first voltage divider resistor, thefirst voltage divider resistor coupled to a first node, the first nodecoupled to a second voltage divider resistor, the first node beingcoupled to a base of a first transistor, the second voltage dividerresistor being coupled to ground; a biasing resistor coupled between VCCand a collector of a first transistor through a second node, the secondnode being coupled to a base of a second transistor, an emitter of thefirst transistor being coupled to ground; and a motor relay coupledbetween VCC and a collector of the second transistor, an emitter of thesecond transistor being coupled to ground, wherein, with the switchopen, the motor relay is disposed to allow the electric motor tooperate, and wherein, with the switch closed, the motor relay isdisposed to disable the electric motor from operating.
 9. A bin-fullsensor for a shredder having a shredder element having blades driven byan electric motor and a bin for collecting shreddant, the sensorcomprising: a T-blade sensor mechanically coupled to and set apart fromthe shredder element, and electrically coupled to the electric motor,wherein the T-blade sensor rotates to a predefined position to select anelectrical contact coupled to the electric motor such that the electricmotor is non-operating when shreddant reaches a predetermined level inthe bin.
 10. The bin-full sensor of claim 9, wherein the T-blade sensorcomprises a pendent blade perpendicularly affixed to a cylindrical body,the cylindrical body having an electrical sensor thereon configured toelectrically connect with electrical contacts on the shredder element.11. The bin-full sensor of claim 10, wherein the pendent blade iscurved.
 12. The bin-full sensor of claim 11, wherein the curved pendentblade is perforated with a plurality of holes.
 13. The bin-full sensorof claim 10, wherein the electrical sensor and electrical contacts forma switch, coupled to the electrical motor.
 14. The bin-full sensor ofclaim 13, further comprising: a microcontroller coupled to the switch,wherein the microcontroller is configured to stop the electric motorwhen the T-blade sensor rotates to the predefined position and theswitch is closed.
 15. The bin-full sensor of claim 13, furthercomprising: a microcontroller coupled to the switch, wherein themicrocontroller is configured to allow the electric motor to turn onwhen the T-blade sensor rotates away from the predefined position andthe switch is open.
 16. The bin-full sensor of claim 13, furthercomprising: the switch coupled between VCC and a first voltage dividerresistor, the first voltage divider resistor coupled to a first node,the first node coupled to a second voltage divider resistor, the firstnode being coupled to a base of a first transistor, the second voltagedivider resistor being coupled to ground; a biasing resistor coupledbetween VCC and a collector of a first transistor through a second node,the second node being coupled to a base of a second transistor, anemitter of the first transistor being coupled to ground; and a motorrelay coupled between VCC and a collector of the second transistor, anemitter of the second transistor being coupled to ground, wherein, withthe switch open, the motor relay is disposed to allow the electric motorto operate, and wherein, with the switch closed, the motor relay isdisposed to disable the electric motor from operating.
 17. A mechanicalbin-full sensor for a shredder driven by an electric motor and having abin for shreddant, comprising: a T-blade sensor electrically coupled tothe electric motor, the T-blade sensor including a pendent, curved, andperforated blade perpendicularly affixed to a cylindrical body, thecylindrical body having an electrical sensor thereon configured toelectrically connect with electrical contacts coupled to the electricmotor, wherein the T-blade sensor rotates to a predefined position toselect an electrical contact such that the electric motor isnon-operating when shreddant reaches a predetermined level in the bin.18. The mechanical bin-full sensor of claim 17, further comprising: amicrocontroller coupled to a switch coupled to the T-blade sensor,wherein the microcontroller is configured to stop the electric motorwhen the T-blade sensor rotates to the predefined position and theswitch is closed.
 19. The mechanical bin-full sensor of claim 17,further comprising: a switch coupled to the T-blade sensor and coupledbetween VCC and a first voltage divider resistor, the first voltagedivider resistor coupled to a first node, the first node coupled to asecond voltage divider resistor, the first node being coupled to a baseof a first transistor, the second voltage divider resistor being coupledto ground; a biasing resistor coupled between VCC and a collector of afirst transistor through a second node, the second node being coupled toa base of a second transistor, an emitter of the first transistor beingcoupled to ground; and a motor relay coupled between VCC and a collectorof the second transistor, an emitter of the second transistor beingcoupled to ground, wherein, with the switch open, the motor relay isdisposed to allow the electric motor to operate, and wherein, with theswitch closed, the motor relay is disposed to disable the electric motorfrom operating.